Characterizing α-phase variants in titanium alloys via EBSD: Understanding colour indexing challenges

Electron Backscatter Diffraction (EBSD) inverse pole figure (IPF) maps are indispensable techniques for visualizing grain orientations in titanium alloys. However, differentiating the twelve α-phase variants formed during the β → α phase transformation, following the Burgers orientation relationship, presents a challenge due to overlapping colours in IPF maps. This study systematically investigates how α-phase variants are coloured in IPF X, Y, and Z maps, using a Ti-6Al-2Sn-4Zr-2Mo alloy sample fabricated via laser-based directed energy deposition of metals. By analysing the orientations of prior-β grains and their α-phase variants with Burgers orientation relationship, we illustrate why multiple variants share similar colours in IPF maps. Additionally, the correlation between IPF map colour distributions and Schmid factors for basal, prismatic, and pyramidal slip systems is explored, providing insights into slip activation and deformation behaviour. This work clarifies how α-phase variants are represented in IPF maps and addressing common ambiguities in interpreting EBSD data, providing a framework for accurate microstructural characterization. These findings highlight the need for complementary techniques to resolve colour-based limitations of IPF maps and support the design of tailored microstructures for improved mechanical performances.